In a principal aspect, the present invention relates to an improved sewing machine head lifter mechanism including means for adjusting the force providing to support the head.
Typically, a sewing machine head is mounted on a cabinet or table. Preferably, the mounting arrangement for the head permits movement of the head into a concealed storage position within the cabinet. Movement of the head between the storage position and use position is augmented by a linkage mechanism attached to the bottom of the sewing machine head. The linkage mechanism is generally counterbalanced to assist in movement of the sewing machine toward an elevated use position. The linkage mechanism also permits movement of the sewing machine head to the interior of the cabinet for storage.
Various types of linkage mechanisms for support and attachment of a sewing machine head to a cabinet have been proposed. A typical linkage mechanism includes a housing which is attached to the interior of a cabinet. A support bracket is attached to the sewing machine head and linkage arms connect the bracket with the housing. The linkage arms pivot to permit movement of the bracket and attached head between a support or extended position and the retracted or storage position. A tension spring provides a means to counterbalance or compensate for the weight of the sewing machine head thereby making it easier to move the head between the projected position and the storage position. A tension spring normally must be customed designed and installed in the linkage mechanism for each model of a sewing machine head since each model of a head may vary in weight. Thus, the support force required for one model head may vary from another type. A desirable objective is to have a multi-purpose, universal head lifter mechanism which may be adjusted to accommodate the weight of the sewing machine head.